269 



(nearly one gallon) over a water bath. The following table will give 

 the result: 



No. One. 

 Iron Pipe. 



No. Two. 

 Logs. 



No. Three. 

 Well. 



Solid matter in 3500 gi-arames, [ •3432 



•3893 7-2000 



In determining the quantity of the several substances indicated by 

 the qualitative analysis, six parcels of water were carefully weighed out. . 

 The object in taking so many parcels was, to avoid the errors that might 

 arise from the accumulation of impurities in the use of chemicals. 

 From number one, the chlorine was extracted ; from number two, the 

 silica, iron, lime, and magnesia; from number three, the iron, mag- 

 nesia, and lime, precipitated on boiling, and which are supposed to ex- 

 ist as carbonates, and the same elements held in solution ; from number 

 four, potassa and soda ; from number five, sulphuric acid ; from num- 

 ber six, allumiua and phosphoric acid. 



In determining the quantity of these substances, it must not be sup- 

 posed that they were obtained and weighed in the forms above ex- 

 pressed, for this was the case with but a single substance — silica. All 

 the rest were weighed in the form of some one of their combinations, 

 and the quantity of the element sought, determined by simple calcula- 

 tion. This process is based on an invariable law in chemical science, 

 that bodies unite in certain fixed and definite proportions, . Thus, chlo- 

 rine was weighed as a chloride of silver. Now, one hundred pai-ts of 

 the chloride of silver invariably contain 24'Y2 parts of chlorine, and 

 75-28 parts of silver. Lime was separated, as a carbonate of hme; 

 magnesia, as a phosphate of magnesia ; potassium, as a chloride of pla- 

 tina and potassium ; sulphuric acid, as a sulphate of baryta, &c. In 

 this manner, the Chemist attains to a degree of minuteness that would 

 appear, to an unpractised person, wholly incredible. Thus a good ba- 

 lance will turn on the 1 -000th part of a grain, (equal to three-tenths of 

 an inch of fine hair.) One-thousandth part of a grain is a weighable 

 quantity ; and yet the one-thousandth part of a grain of chloride of 

 silver contains but the l-4000th part of a grain of chlorine, a quantity 

 too small to be weighed, but one which may be calculated. It may be 

 proper to state that the balance used was Robinson's, of the best Ger- 

 man manufacture. To avoid friction, the pans and beam are suspend- 

 ed on knife edges, and highly polished camelian. 



